The present invention relates to the field of sampling and analysis of geological formations for evaluating and testing the formations for purposes of exploration and development of hydrocarbon-producing wells, such as oil or gas wells. More particularly, the present disclosure is directed to methods and systems utilizing a downhole apparatus having an array of sensors that is configured or designed with discrete, independent sensors having individualized control and communication functionality. In this, the present disclosure provides downhole sensor system architecture for well logging tools utilizing plug and play configurations that are configured or designed for downhole oilfield applications.
Downhole sampling and analysis is an important and efficient investigative technique typically used to ascertain characteristics and nature of geological formations having hydrocarbon deposits. In this, typical oilfield exploration and development includes downhole sampling and analysis for determining petrophysical, mineralogical, and fluid properties of hydrocarbon reservoirs. Such characterization is integral to an accurate evaluation of the economic viability of a hydrocarbon reservoir formation.
Typically, a complex mixture of fluids, such as oil, gas, and water, is found downhole in reservoir formations. The downhole fluids, which are also referred to as formation fluids, have characteristics, including pressure, temperature, volume, among other fluid properties. In order to evaluate underground formations surrounding a borehole, it is often desirable to characterize the fluids, including composition analysis, fluid properties and phase behavior. Wireline formation testing tools are disclosed, for example, in U.S. Pat. Nos. 3,780,575 and 3,859,851, and the Reservoir Formation Tester (RFT) and Modular Formation Dynamics Tester (MDT) of Schlumberger are examples of such tools.
Recent developments in downhole sampling and analysis include techniques for isolating and characterizing formation fluids downhole in a wellbore or borehole. In this, the MDT may include one or more fluid analysis modules, such as the Composition Fluid Analyzer (CFA) and Live Fluid Analyzer (LFA) of Schlumberger, for example, to analyze downhole fluids sampled by the tool while the fluids are still located downhole. In such downhole sampling and analysis modules, formation fluids that are to be sampled and analyzed downhole flow past a sensor module associated with the sampling and analysis module. Such downhole sampling and analysis modules also typically include other sensor types to acquire relevant and important data regarding the geological formations.
In typical sensor modules of the type described above, the sensors are an integral part of the module, and the downhole tool is configured or designed for operation with a fixed and specific sensor configuration. In this, addition or removal of a sensor unit requires redesign and reconfiguration of the tool including control and communication functionality associated with the tool. Increasing the size of a sensor array means that the overall tool size has to be increased to accommodate the additional sensor units. Similarly, repair of one or more sensor unit requires that the complete tool be shipped or transported for the required operation. In addition, field testing of new sensor designs is done by building a new tool prototype including the new sensors which adds complexity to new sensor development and testing.
As the design and development of new sensors has progressed and the capability of downhole analysis has grown a need has been felt for flexible and configurable downhole tool architecture that provides easy sensor attachment and removal. In this, the availability of downhole sensors that are discrete units having independent control and communication capability would eliminate some of the limitations that exist in typical fixed architecture sensor systems for downhole analysis.
Accordingly, it will be appreciated that there exists a desire to improve upon conventional downhole sensor systems in order to make the systems more flexible and adaptable for downhole applications. The present applicants recognized that existing downhole systems of the type described above could be improved by implementing new mechanical, electrical and software infrastructure that facilitates discrete, modular sensor units based on plug and play architecture.
The limitations of conventional systems noted in the preceding are not intended to be exhaustive but rather are among many which may reduce the effectiveness of previously known downhole systems. The above should be sufficient, however, to demonstrate that downhole sensor systems existing in the past will admit to worthwhile improvement.